Hi,

my "doubt of the day" is the following...

If I play "Lethal counterattack" and my opponent plays "the Hand's Judjement" I have to kneel 2 stark char anyway??? Event cost must be paid also if event is cancelled?

Yep, here is the relevant FAQ entry:

(3.4) Paying For Cancelled Effects
Effects that are canceled are still considered
to have been played. Only the effects are
canceled. Costs have still been paid, and any
target is still chosen.

More to the point, before someone can even play The Hand's Judgment, the cost of Lethal Counterattack has already been paid. You can't go backwards and unpay the cost.

thx for the clarification

And if an event has a "Then, if X, ..." statement, must I pay also the costs for the second part? What if it is canceled?

You don't have to pay costs for "Then..." effects. Everything after the "Then" is considered part of the event's effects, so you never get to that if the event is canceled (because you do not resolve any of the events effects when it is canceled).